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[05omegav6]

I would replace hoses and rebleed then... if the pedal holds pressure engine off, then the seals are fine.

[Shackeng]

I would replace hoses and rebleed then... if the pedal holds pressure engine off, then the seals are fine.

I still find it hard to believe that the hoses have gone so soft on such a low mileage car. It only did 18k in its first eight years, so I suspect either seal hardening or lack of fluid changing in that period may have caused the seals to deteriorate.

[05omegav6]

So the seals can go hard from lack of use, yet the hoses, exposed to uv light and weather cannot degrade at all?

[Kevin Wood]

Engine off I think... pump pedal until solid, then press and hold. If it softens or sinks further the seals are shot allowing for the two exceptions given above

Best to do this test with the engine running, so you can exert normal pressure on the master cylinder with assistance.

[05omegav6]

Engine off I think... pump pedal until solid, then press and hold. If it softens or sinks further the seals are shot allowing for the two exceptions given above

Best to do this test with the engine running, so you can exert normal pressure on the master cylinder with assistance.

But won't that give an ambiguous result by virtue of the continuous vacuum

[Kevin Wood]

If you have the engine running, and apply normal braking pressure, then hold it for maybe a minute or more, does the pedal continue to sink after the initial application of the brakes?

Might be worth trying another V6 if someone amenable is nearby, just to make sure it's not "TADTS".

Also, if the car does minimal miles, it's possible that the brake friction surfaces have got a bit glazed, I suppose.

[Kevin Wood]

Engine off I think... pump pedal until solid, then press and hold. If it softens or sinks further the seals are shot allowing for the two exceptions given above

Best to do this test with the engine running, so you can exert normal pressure on the master cylinder with assistance.

But won't that give an ambiguous result by virtue of the continuous vacuum

No. All you're checking is that if the master cylinder has a constant force on it, and therefore you have constant pressure in the braking system downstream of it, you don't get leakage out of the system. Any leakage and the volume of fluid in the system reduces and you have to move the pedal down to keep the pressure exerted.

All the servo is doing is using engine vacuum to increase the pressure on the MC. The pedal still moves with the MC's piston, so the test is valid with the engine on, it's just that it greatly increases the effort you can exert on the MC piston.

[Marks DTM Calib]

You cant compare the two vehicles as the 3.2 has the power stop servo which gives a more progressive brake pedal

[Shackeng]

So the seals can go hard from lack of use, yet the hoses, exposed to uv light and weather cannot degrade at all?

It would be interesting to know if this is common, on any vehicle, I have heard of it but suspect it is rare on low mileage cars. Are modern brake pipe materials are more prone to softening? I have had to change these for becoming hard and brittle with age on an old Ford once many years ago, I think it was a Cortina

[Shackeng]

If you have the engine running, and apply normal braking pressure, then hold it for maybe a minute or more, does the pedal continue to sink after the initial application of the brakes?

Might be worth trying another V6 if someone amenable is nearby, just to make sure it's not "TADTS".

Also, if the car does minimal miles, it's possible that the brake friction surfaces have got a bit glazed, I suppose.

Yes.

[Marks DTM Calib]

So the seals can go hard from lack of use, yet the hoses, exposed to uv light and weather cannot degrade at all?

It would be interesting to know if this is common, on any vehicle, I have heard of it but suspect it is rare on low mileage cars. Are modern brake pipe materials are more prone to softening? I have had to change these for becoming hard and brittle with age on an old Ford once many years ago, I think it was a Cortina

Net to bugger all UV light can get near them, rubbers can suffer from oxidisation but I suspect the effect you are experiencing is the power stop servo.

[Shackeng]

So the seals can go hard from lack of use, yet the hoses, exposed to uv light and weather cannot degrade at all?

It would be interesting to know if this is common, on any vehicle, I have heard of it but suspect it is rare on low mileage cars. Are modern brake pipe materials are more prone to softening? I have had to change these for becoming hard and brittle with age on an old Ford once many years ago, I think it was a Cortina

Net to bugger all UV light can get near them, rubbers can suffer from oxidisation but I suspect the effect you are experiencing is the power stop servo.

Can you tell me anything more about this Mark? where is it, can it be fixed easily etc./

[chrisgixer]

Seem to remember a tis entry explaining a two stage level of assistance. The first stage being very gradual to keep the chauferd gent in the back happy. Yet if the driver stamps on the brakes he gets more assistance in an emergency.

I guess Marks post implies your symptoms are entirely normal if that's the case. And I need to fit a servo off a TD to get rid of the shite pedal feel on mine.

[Marks DTM Calib]

Exactly, the facelift received a two stage power stop servo which gives a gradual pedal but a bucket load of additional assist if you press harder.

Cant comment on if the earlier servo is a direct replacement (probably is knowing GM)

[Shackeng]

I guess I need a FL V6 owner to try mine for comparison. Thanks for all the input guys, very informative and helpful as usual.
I would be glad to know if anyone has experienced these bulging brake pipes on their Omega described above.